A number of medical procedures involve identification of, localization of, and/or insertion of a medical instrument into a suspicious breast lesion. For example, such procedures may be utilized to detect or diagnose the nature of a lesion, to ablate or remove a lesion, to deliver a drug or other treatment to the lesion, or to mark a pathway to the lesion for use in subsequent open surgery.
One application of such procedures relates to the detection of breast cancer. Breast cancer is a leading cause of death of women in the United States. Early detection and analysis of breast lesions suspected of being cancerous is therefore of great importance. Accordingly, women increasingly undergo routine mammography to detect suspicious lesions which may not be palpable and which can therefore escape detection through self-examination. In many cases, an initial screening or diagnostic mammography procedure identifies a suspicious lesion which can then be analyzed through a biopsy procedure.
Detection of non-palpable lesions can be accomplished through x-ray imaging. In order to obtain a complete image of a breast, two x-ray images per breast, e.g., a top or cranial-caudal view and a side or medial-lateral view, are commonly utilized although some believe that a single, oblique view, commonly called a "Cleopatra" view, may be sufficient for this purpose. As used herein, the phrase "oblique views" refers to views of a breast from directions transverse to the plane in which conventional top and side views are taken. Current mammographic systems generally do not provide positioning flexibility to easily obtain a Cleopatra view. Thus, a complete imaging procedure normally involves obtaining four x-ray views, two views per breast. This can be time consuming and exposes the patient to four intervals of x-ray radiation. Similarly, due to the lack of flexibility in positioning current mammographic systems to the patient's breasts, the patient is ordinarily positioned to the equipment, e.g., the patient is ordinarily moved in order to sequentially examine the left and right breasts, and the patient's breast and arms are moved with the assistance of an operator in order to achieve a high quality mammographic image, thereby further complicating the procedure.
If a suspicious lesion is identified through screening or diagnostic mammography, further definition of the nature of the lesion, i.e., malignant or benign, normally involves surgical biopsy of the suspicious area following a needle localization procedure to mark the non-palpable lesion for the surgeon. Needle biopsy procedures of either fine needle aspiration (i.e., to obtain cell samples for cytological analysis) or core biopsy (i.e., to obtain a tissue sample for histological analysis) are gaining acceptance as a minimally invasive alternative to surgical excisional biopsy. In this regard, it will be appreciated that tissue samples from core biopsy are preferred over cell samples because such samples permit histological examination of the lesion, not merely cytological examination, thereby providing a definitive diagnosis and reducing or eliminating the need for a specialized cytologist.
The screening and diagnostic mammography and certain stereotaxic needle biopsy procedures have generally been performed with the patient either in a vertical sitting or standing position or in a face down, horizontal position, wherein one of the patient's breasts protrudes through an opening in the examination table. The sitting or standing position is advantageous for certain procedures as easy access to the breast is provided for the technologist and equipment. In addition, the sitting or standing procedures do not require an examination table mounting and dismounting process which can be difficult for some patients. On the other hand, the horizontal position has been found advantageous in that the breast is pendulantly disposed thereby facilitating positioning of the breast for mammographic procedures and access to lesions near the chest wall. In addition, the horizontal position allows small breasts to be compressed more efficiently. Such breast compression is desired during mammographic procedures. The horizontal position also enhances patient comfort and reduces the likelihood of movement of the breast during a mammographic and particularly a needle biopsy procedure. Further, a safety advantage is obtained when the patient is in a horizontal position as there is always a risk of fainting during the procedure.